Method of signaling



NOV- 11, 1930. L. A. BRIGGs 1,781,361

METHOD OF SIGNALING INVENTOR LOYD A. BRIGGS AT RNEY NOV- 11, 1930. L. A. BRIGGS 1,781,361

METHOD OF SIGNALING F'iled Aug. 13, 1928 2 Sheets-Sheet 2 lINVENTORS LOYD. A. BRIGGS Patented Nav. 11, 1930 UNITED ASTATES PATENT OFFICE LOYD A. BRIGGS, 0F CRNFORD, NEW JERSEY, ASSIGNOR TO RADIO CORPORATION OF AMERICA, A CORPORATION 0F DELAWARE METHOD OF SIG-NALING Application filed August 13, 1928. Serial No. 299,219.

The present standardized method of signaling by keying a radio transmitter utilizes two signal values, that is a signal frequency for-marking and no signal for spacing or two signal frequencies, one for marking and one for spacing. In this method of signaling which is known as the normal dot and dash method the length of a space between characters is equal to the length of a dot and the length of a space between letters is three times the length of a dot while the length of a dash is equal to three times that of a dot. In thiswmethod of signaling transmission involves the total loss of the time used in spacing and also the extra time required to transmit dashes i. which take three times as long to-send as a dot. The time utilized for spacing is wasted, i. e. the transmitting apparatus is idle during that time.

The primary object of this invention is to provide a method of signaling whereby the idle time used for spacing is usefully employed and the aggregate speed of transmission can be materially increased.

Briefly and broadly, this object is attained by utilizing the time which heretofore has been wasted by spacing, and by transmitting a dash which took a time interval three times the time interval required to send a dot.

This is accomplished by transmitting on a plurality of channels, three signal values being used on each channel. These three signal values are sent out on a single Channel, according to the standard Morse code, and generally the dots are positive or of one frequency, the spaces are no signals or zero with reference to the dot while the dashes are 'negative or of a different frequency. For maximum efficiency five values of signal are used, that is four signal values for marking and a fifth signal value for spacing. The use of five signal values as indicated above produces two channels and is required to secure full eciency of the method.

For use on high speed transmitters, the number of signal values may be increased to seven, that is, six signal values for marking with no signal or the seventh signal value for spacing, or nine or even eleven signal values or more to produce several slow speed channels. Where nine signal values are used, eight frequencies may be used for marking and no signal for spacing or a ninth frequency may be used for spacing. The use of seven, nine, eleven, or more signal values will produce three, four, five, or more channels.

In each of the above-cases the spacing or interval value may be no signal or an additional frequency depending upon the type of transmitter being used. The purpose of providing the odd orinterval frequency is to provide the interval between Morse characters in cases Where such -an interval occurs simultaneously on both channels.-

Another object of this invention is to provide a novel transmitter which though simple in structure and operation will transmit signals on a plurality of channels according to applicants novel method.

Preferably, I accomplished these objects .by the use of automatic transmitters at the transmitting end for keying the transmitter itself, each of which consists of a plurality of VVheatstone cable transmitters, there being one for each channel, driven by the same motor and shaft, but otherwise entirely independent of each other.

A valuable feature of this invention is that transmission may be secret. This secrecy is afforded by transmission of dots and dashes on two different frequencies and also by the fact that on successive days or hours or even shorter intervals the actual frequencies used for the dots and dashes 'of either signal channel and for intervals can be reassigned and used for different purposes.

A further advantage to be gained by the use of my novel method is that the signals transmitted according to this method may be received Vby aural reception, that is, by distinguishing the dots and dashes by their different tones, or the may be received by the use of an ink recor er. Both of these methods of reception are in general use and' therefore signals sent according to my novel method may be received by receiving apparatus now in use without materially altering said apparatus. A

@ther advantages will become apparent in part from the specification and in part therefrom when read inv connection with the accompanying drawing by which the actual operation of this system can best be illustrated graphically.

Figure 1 illustrates graphically my novel method of transmitting; while Figure 2 shows one arrangement of the apparatus necessary to carry out the novel method of transmitting illustrated by F igure 1. l

In Figure 1 of the accompanying drawing, in which each section in a vertical direction represents one unit of transmitter time;

Line 1 represents the present normal method of signaling in which two values are' used, usually signal and no signal and where a dash is three times the length of a dot.

Line 2, represents the cable method of signaling in which three values are used, usually positive for dot, negative for dashes and no signals for spaces.

Line 3-A represents the cable method applied to channel A of the improved method where frequency 1 is used for dots, frequency 2 for dashes and any other frequency or no signals for spaces.

Line 3-B represents channel B of the improved method where frequency 3 is used for dots, frequency for dashes and any other frequency, or no signals for spaces.

Line -C represents the composite signal as actually transmitted into the air.

Line 4 represents the composite signal when transmitted after a reassignment of frequencies to obtain secrecy. 1

Lines 5-A, -B, and 5-C, show graphically my novel method of application to secure slower channels in words per minute with the same fundamental speed of transmission, while,

Line -D shows the composite transmitted signals of lines -A, -B and 5-C.

An explanation of my novel method whereby maximum efficiency is obtained will now be given. This method which utilizes five signal values thereby securing two channels will be suicient to show the application of my method and advantages to be gained thereby. Since additional channels may be obtained by the use of additional signal values in the same manner that two channels are obtained by the use of five signal values an explanation of the method using five values and thereby securing two channels will be sufficient to show its application and'advantage. The use of additional values to secure additional channels will then be self-evident it is thought.

Line 1 of the drawing represents the present normal method of signaling in which two values are used, usually signal and no signal and where' the dash is three times the length of a dot.

Line 2 vrepresents the cable method of signaling in which 3 values are vused, usually,

positive for dots, negative for dashes and no signals for spaces. The wordsilkyis shown in lines 1 and 2. However, it will be noted that the time requiredto transmit silky by the method used in line 2 is much less than the time required to transmit it by the method used in line 1.

In my improved method of signaling the standard Morse code is used on each channel employing one frequency for dots on A channel, a second frequency for dashes on.

A channel, a third frequency for dots on B channel and the fourth frequency for dashes on B channel. Dots and dashes are of equal length and are used as in cable practice, recording dots above and dashes below a center line. This in itself increases the speed of each channel by a well known percentage over that possible when the dash is three times the length of the dot. Each of the two channels will operate at the same speed possible on the single channel obtained by the for dots, frequency 4 for dashes and any other frequency, or no signal for spaces. In this line the word twelve is shown.

Line 3-C represents the composite signal as actually transmitted into the air. As shown channels A'and B of lines S-A and 3-B respectively, are combined to send out the composite signals shown in line 3-C The two frequency values on each of the channels A and B of 3-A and 3--B are denoted by the numerals 1, 2, 3 and 4 in line S-C, the interval frequency, denoted by the numeral 5, is used'only when spacing occurs simultaneously on both channels.

It will be noted that in my improved method in which the cable method is applied to each channel thereof I so coordinate the keying apparatus that the space units of channel A are utilized for the dot or dash signaling units of channel B and the space units of channel B are utilized-for the dot or dash signaling units of channel A. This feature of my improved method which utilizes all of the signaling time to send signals produces the chief value of this system over transmitting systems heretofore used in which much of the sending time was occupied in sending extra long dashes and spaces. As will be noted from the drawings the time required to send either the word twelve or the word silky according to the old method 1s longer than the time required to send both words according to my novel method.

It is quite within the known range of a transmitter to produce and efficiently radiate several different frequencies as the tuning.

values of the transmitter are altered by keying, and in carrying out my novel method of transmitting the several frequencies may be produced by altering the inductance or capacity values of the tuned circuits of the transmitter. These frequencies differ from each other by several cycles, several hundred cycles or several kilocycles, depending upon the fundamental frequency employed. Thus for an arc or tube transmitter on 16,000 cycles the five frequencies might be 16,100, 16,050, 16,000,"15,950 and 15,900 cycles, easily separated and distinguished at the receiver by well known methods of tuning and ltering. For a short wave transmitter operating on 18,0001kilocycles, the five frequencies might be 18,004 kc., 18,002 kc., 18,000 kc., 17,998 kc., and 17,996 kc., also, easily separated and distinguished at the receiver by present methods of tuning and filtering, and in this case allowing for a reasonable amount of frequency variation of the transmitter. It is therefore unnecessary to go into any further detail as to the transmitter itself or the receiver itself. The application of my novel method of transmitting may now be shown by considering the terminal apparatus at the sending end of the circuit and at the receiving end. The automatic transmitters at the sending end, for keying the transmitter itself will consist of two Wheatstone cable transmitters driven by the same motor and shafting or otherwise synchronized, but otherwise entirely independent of each other and being controlled by a plurality of the usual perforated slips, the number of slips depending on the number of channels used. In the case where five signal values are used on two channels, two perforated slips will be required, one for each channel. The connection between the two Wheatstone cable transmitters and the motor will be such that the spacing interval of one coincides with the marking interval of the other.

A more complete understanding of the automatic transmitting apparatus and the operation thereof will be had from Figure 2 of the drawings, in which is illustrated one arrangement of apparatus used to carryout my novel method. In this figure 1 and 2 are cable type Wheatstone transmitters controlled by two separate perforated slips, not shown, to transmit on channels A and B respectively. The transmitters 1 and 2 which are otherwise independent of each other are driven in synchronism at the same rate of speed through gears 21 and 22 respectively by motor M. The connection between the automatic transmitters 1 and 2 and the gears 21 and 22 respectively on the motor shaft is such that the spacing interval of one transmitter coincides with the marking interval of the other, and vice versa. That is, the plunger contacts of auto transmitter for A channel are always up when the plung'ers on auto transmitter 2 for B channel are down and vice versa. The auto transmitters 1 and 2 are connected by wires 3, 4,

5 and 6 respectively to control relays 7 and 8 and, 9 and 10 respectively, which relays in turn when energized close contacts 11 and 12 and, 13 and 14 respectively. In this manner the value of induct'ance 15 in the radio transmitter 16 is varied thus varying the Ifrequency of the signal transmitted in accordance with the perforations in the perforated slips controlling the auto transmitters 1 and 2.

In the brief description of the keying operation of the auto transmitters which follows it will'be assumed that dot elements represented by line 1 of channel A (line 3 Figure 1) are sent out at frequency f1 which is the highest frequency used while the dash elements line 2 of channel A and dot and dash elements of channel B represented by lines 3 and 4 respectively are sent out on frequencies f2, f3 and f, which decrease progressively or otherwise with respect to f1. A fifth frequency f5 represented by line 5 of composite signal 3C is used when a spacing interval occurs on channels 3A and 3B simultaneously.

In transmitting according to my novel method the words silky and twelve on channels A and B respectively under the above assumed conditions, the first signal element a dot of the letter s of silky (see lines 3A, 3B and 8C) on channel A is obtained by keying auto transmitter A to close line 3 (see Figure 2) energizing relay 7 to close contact 11. This short circuits a portion of inductance 15 and an electrical impulse at a frequency f1 is sent out by transmitter 16. This signal element is represented by the first dash in line 1 of the composite signal 3C. The neXt signal element a dash representing the letter t of twelve on channel B is obtained by keying auto transmitter B to close line 6, energize relay 10 and close contact 14. This short circuits a small portion of the inductance 15 and a signal impulse at a frequency f, lower in this case than the frequency f1 is sent out by transmitter 16. This signal element vis represented by the first dash in line 4 of the composite signal 3C. The next signal element a dot of the letter s of silky on channel A represented in line 1 of 3A is obtained by keying transmitter A to close contact 11. A signal element at frequency f1 is again sent out by transmitter 16. This dot on channel A is followed by a spacing interval which occursat the same time as a spacing interval on channel B. This spacing interval (which occurred on both channels lll() simultaneously) is represented in the composite signal 3C by a unit in line 5 and is obtained when all of the contacts 11, 12 etc. are

open leaving all of the inductance 15 associated with the transmitter 16 so that a signal element at frequency f5 is sent out by transmitter 16.

As pointed out elsewhere in the specification the transmitters A and B are so coordinated and the strips so perforated that but one contact member 11, 12, etc. is closed at one time, and accordingly only a -definite predetermined portion of the inductance 15 is short circuited at each keying operation.

These assumptions are made merely for purposes of illustration as it will be 'understood that various combinations of frequences may be used on each channel, -and that the interval value may be no signal.

The receiving end may be operated by the use of aural reception distinguishing the dots and dashes by their different tones, which is nothing new, or by the use of an ink recorder operating upward on the dot frequency and downward on the space frequency, this last method of receiving signals being also well known.

Actual reception of the transmitted radio signals may be accomplished by the use of a separate receiver for each frequency iemployed or, if the transmitting frequencies are sufficiently close to each other, two or more frequencies may be received on the same receiver and separated by tuning methods or by the use of proper audio frequency filters..

An illustration of the method of application to secure slower channels in words per minute with t-he same fundamental speed of transmission is illustrated in lines 5-A to 5-D in which 5-A shows channel A, 5-B shows channel B and -C shows channel C. The composite of the seven frequencies actually transmitted appears in line 5 1). In

view of the detailed description of my novel method of transmitting signals by the use of 5 signal values on 2 channels as given above, this brief description of the method of adding channels by additional frequencies and the method of time division per channel will be sufficient.

A very valuableffeature of this system is the comparative secrecy afforded by transmission of dots and dashes on two different frequencies and by the fact that on successive days or hours or even at shorter intervals, the actual frequencies usedfor the dot-s and dashes of either channel, and for intervals can be reassigned and used for different purposes, Without any involved alterat-ion in methods or apparatus at either end. For in-l stance, when signaling, according to my novel method which uses ve signal values on two signal channels, the frequencies. 2 and 5 could be used for dots and dashes of channel -A, frequencies 4 and 1 for dots and dashes without increasing the fundamental keying speed thereof. My novel method is also applicable to channelling whereby several slow speed channels are obtained, the total speed of all channels however totalling exactly the same as the two normal speed channels otherwise obtained by this method. The terminal apparatus is extremely simple and does not require synchronization of transmitting and receiving instruments.

Although described and' illustrated herein in its specific application to radio communication my novel signaling method is equally applicable to communication over wire lines or cables. The same advantages of increased speed, increased capacity, and of multiplexing by obtaining` several channels, are derived when applied to wire or cable communication as when usedv for radio communication.

What I claim is:

1. The method of increasing the speed of signaling which includes signaling simultaneously on a plurality of channels and utilizing the spacing time of one lchannel as the marking time of another channel.

2. The method of increasing the speed of signaling which includes signaling on a plurality of channels simultaneously and coordinating said signals in such va manner that the spacing units on one channel are utilized as the marking units on another channel.

3. The method of cable code signaling with autotransmitters which includes, signaling on `a plurality of channels simultaneously, providing a plurality of frequencies for each channel for the marking units, and coordinating the keying of said auto transmitters in such a manner that the spacing units of one channel are utilized as 4the marking unit of another channel.

4. The method of signaling with auto transmitters which includes, signaling on a plurality of channels simultaneously, providing a plurality of frequencies for each channel for marking, providing a frequency for intervals and coordinating the keying of said auto transmitters in such a manner that the spacing units of onechannel are utilized as the markin unit of another channel, and the interval requency is utilized when a spacing unit occurs simultaneously on all channels.` y

5. The method of signaling by means of a radio frequency transmitter controlled by auto transmitters of the cable type which includes, transmitting on a plurality of channels simultaneously, keying said auto transmitters to obtain a plurahty of frequencies on each channel for marking, synchronizing said auto transmitters, and coordinating said auto transmitters so that the spacing units ofone channel are used as the marking units of another channel.

6. The method of signaling by means of a radio frequency transmitter controlled by auto transmitters of the cable type which includes, transmitting` on a plurality of chanv`:maling on a plurality ofchannels simultane- Iously, providing a fre uency on each channel for dashes, provi ng a 'frequency on each channel for dots, and coordinating said transmitters in such a manner that the spac ing units of one channel are utilized as the dot and dash units of another channel.'

i 8. The method of signaling by means of a radio frequency transmitter controlled by auto transmitters of the cable type which includes, transmitting on a plurality of channels simultaneously, keying said auto transmitters to obtain a frequency for dashes on each channel, keying said auto transmitters to obtain a frequency for dots on each channel, synchronizing said auto transmitters, f

and coordinating said'v auto transmitter so that the spacin units of one channel are lutilized as the ot or dash units of another 9. In radio apparatus the combination of a transmitter adapted to transmit a plurality of marln'ng frequencies alternated with spacing frequencies on a plurality of channels, meansl comprising a plurality of automatic transmitters for controllin the frequency transmitted by said transmitter, and means for keying said auto transmitters in such a manner that the spacing units on one of said channels are utilized as the marking units on another lof said channels.

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